The drying of concrete and brick structured floors has been traditionally effected by using e.g. condensing or absorption dryers. However, such prior art dryers are relatively slow. Faster drying has been attempted by introducing microwave or infrared dryers. One solution, which involves the use of an infrared dryer, has been described in EP 0 979 378 B1. Prior known are also flat surface dryers, which are provided with a separate hot-air fan for blowing into a targeting box and with a separate exhaust fan for discharging the air blown into the targeting box. Such foregoing solutions, one of which will described more precisely hereinbelow, represent the closest prior art.
A flat surface dryer according to the prior art has been described in Fl 105500 B. The apparatus disclosed in this cited publication consists of an air guidance box with its sealing, said air guidance box being placed against a surface to be dried. The air guidance box is fitted with a fan for blowing heated air into the interior of the air guidance box. An objective is to guide the heated air for spreading it as effectively as possible over the entire section of a surface to be dried which is covered by the air guidance box. This is effected by using air guides integrally secured to the air guidance box. Drying air is discharged by way of a discharge hose. The discharge hose may also be fitted with a separate fan for an enhanced discharge of air from the targeting box.
The prior art equipment involves several drawbacks, impeding use of the equipment. For example, the use of microwave dryers in an apartment building entails that apartments below the one being dried be also evacuated of inhabitants for the duration of a drying process. This causes undue inconvenience for other inhabitants of the apartment building. In addition, microwaves may be harmful for existing heating, plumbing, ventilation and electrical installations.
Infrared drying is an option somewhat speedier than traditional condensing or absorbing dryers, but still the drying of a drenched concrete slab cannot be managed within a week. In addition, due to a partially uncovered design of the apparatus, some of the thermal energy burdens unnecessarily the environment.
Drawbacks in the solution disclosed in Fl 105500 B include an energy demand of the apparatus which is high in view of the attainable drying result. In other words, the apparatus has a very poor efficiency. The apparatus has an energy consumption of about 1500-2000 W/m2 to be dried. The apparatus has a high demand for replacement air and thus the space to be dried must be provided with unobstructed supply of air. In practice, this means (especially in apartment buildings) that the door or window to a space to be dried must be left open. The doors open to other parts of the apartment increase the level of inconvenient noise in the apartment, degrading living conditions. At the same time, the thermal load emerging from the drying apparatus proceeds at least partially to other parts of the apartment.
The high demand of energy per unit area to be dried also limits the number of drying devices as the supply of energy is often a limiting factor regarding the number of apparatus units. This also hinders the drying of extensive areas to be dried or requires separate arrangements for supplying electric power to the dryers.
The use of several dryers in one and the same space requires an especially large amount of replacement air and produces an equal amount of moist and hot exhaust air. The management of such quantities of air is likely to confuse the building's ventilation unless separate ducting is provided all the way out, for example across a window or a balcony. Such assembly of duct systems has to be done quite often through inhabited rooms, affecting seriously the living conditions or possibly even inhibiting the use of an apartment during the drying process. In addition, the continuously open doors allow the rest of the apartment to be pervaded by a thermal load and noise (running sound of the dryer motor) delivered by the apparatus.
In some cases, the supply of adequate replacement air and the discharge of abundant exhaust air is not possible by way of open windows or doors. Reasons for this include e.g. unauthorized passers-by, cold weather in winter, snowfall, rain or another reason like that.
The prior art apparatus units involve problems also in terms of providing a consistent distribution of thermal energy over the entire area to be dried. Minor leaks between a floor surface and a targeting box confuse effectively the movements of air within a targeting box. Moreover, adjustment (ratio between blowing and suction rates) of the apparatus is difficult.
Warming of the electrical components in drying equipment, due to the pervasion of abundant hot exhaust air into the surroundings and due to a high conduction of heat through a dryer's structures to electrical equipment, causes significant problems in terms of operating reliability of the electrical equipment.